I am putting together a pair of JBL L150 speakers and only need the mids which should not be hard to find as there are different ones that fit. But I am in need of the crossovers, I do have one but am pretty sure that it has issues and have read that there are upgrades that can be done. Is there anybody out there that builds crossovers or rebuilds existing ones as I do not have the expertise to do either. I am around Chicago and shipping should not be an issue.